Nema23 motors are widely and fairly cheaply available on ebay, but which ones ? And how good/bad would they be ?
First welcome to the forum. Ok you won't go far wrong with these :https://www.cnc4you.co.uk/Stepper-Mo...YGH301B-Nema23 or http://www.zappautomation.co.uk/elec...per-motor.html
It all depends if you want to reuse the parts you are buying when you decide to build a stronger machine if so buy wisely as rubbish drives and motors will disappoint. Also keep away from any kits you see as they are never matched.

look for drives like AM882 leadshine.

Read through some of the build logs on here to get inspiration Then put a design up and ask questions. Good luck with the build